You can enroll in Medicare Part A during specific windows, and missing them can cost you thousands in penalties

Medicare Part A covers hospital stays, skilled nursing care, hospice, and home health services. You become may be able to access at 65, but the enrollment window matters: sign up during your Initial Enrollment Period (the seven-month window that starts three months before the month you turn 65) and you pay no penalty. Wait past that window, and you'll pay a permanent 10% surcharge on your Part A premium for as long as you have Medicare — even if you enroll years later.

The rule is simpler if you're already receiving Social Security or Railroad Retirement Board benefits: you're enrolled automatically in Part A the month you turn 65, with no action needed. If you're not yet taking Social Security, you must enroll yourself during that seven-month window or face the penalty.

Key Takeaways

  • Your Initial Enrollment Period runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after.
  • If you're receiving Social Security or Railroad Retirement Board benefits, you're enrolled in Part A automatically at 65 with no action required.
  • If you're not yet taking Social Security, you must enroll yourself during your Initial Enrollment Period to avoid a permanent 10% premium penalty.
  • You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • Special enrollment periods exist if you lose employer coverage or move to a new state, extending your window beyond the standard seven months.

Your seven-month enrollment window explained

The Initial Enrollment Period is a fixed seven-month span centered on your 65th birthday month. It begins three months before that month and ends three months after. For example, if you turn 65 in June, your window opens in March and closes in September.

During this window, you can enroll without penalty, regardless of your health status. Medicare Part A has no medical underwriting — they cannot deny you or charge you more based on your health history. This is one of the few times in Medicare when your past medical conditions don't affect your coverage or cost.

The penalty for late enrollment is permanent. If you miss your Initial Enrollment Period and don't have a may have access to reason, your Part A premium increases by 10% for as long as you're enrolled. That surcharge stays with you even if you enroll five years later or ten years later. The only way to avoid it is to enroll during your window.

When you're automatically enrolled

If you're already receiving Social Security retirement benefits or Railroad Retirement Board benefits before you turn 65, Medicare Part A enrollment happens automatically. You don't fill out a form or call anyone. The month you turn 65, you'll be enrolled in Part A, and your Medicare card will arrive in the mail about two weeks before your coverage starts.

You'll still receive information about Part B (medical insurance) and other coverage options, and you'll need to make choices about those. But Part A itself requires no action on your part if you're already collecting retirement benefits.

If you're not yet taking Social Security when you turn 65, you must enroll in Part A yourself during your Initial Enrollment Period. Many people in this situation are still working or have delayed claiming benefits for other reasons. The enrollment window doesn't change — it's still seven months — but the responsibility is yours to initiate it.

How to enroll during your window

You have three main routes to enroll in Part A:

  1. Online at Medicare.gov: Go to the Medicare enrollment page, create or log into your account, and follow the enrollment steps. This is fastest if you have your Social Security number and basic information ready. You'll get confirmation when ready.
  2. By phone: Call 1-800-MEDICARE (1-800-633-4227). Representatives can walk you through enrollment and answer questions about your specific situation. Wait times are typically shorter early in the morning or mid-week.
  3. In person: Visit your local Social Security office. Bring your Social Security card, proof of citizenship or legal residency, and proof of age (birth certificate or passport). You can find your nearest office at ssa.gov.

Whichever route you choose, have your information ready: your full name, date of birth, Social Security number, and citizenship status. The process itself takes 15 to 30 minutes, and you'll receive written confirmation of your enrollment.

Special enrollment periods if you miss your window

If you miss your Initial Enrollment Period, you may still enroll without penalty during a Special Enrollment Period if you have a may have access to reason. The most common may have access to reasons are losing employer health coverage or moving to a new state where your current plan no longer works.

If you lose employer coverage — either because you retired, your employer dropped the plan, or you were laid off — you have eight months from the date coverage ends to enroll in Part A without penalty. You'll need to show proof of when your employer coverage ended, such as a letter from your employer or your final benefits statement.

If you move to a new state and your current Medicare plan doesn't serve your new location, you may have a Special Enrollment Period to switch plans. The timing varies depending on your situation, so contact Medicare directly at 1-800-MEDICARE to confirm whether you may have access to.

Other may have access to reasons include becoming a U.S. citizen, gaining legal residency status, or having Medicare information errors corrected. Each situation has its own rules about how long you have to enroll. If you think you have a may have access to reason, call 1-800-MEDICARE to discuss it before assuming you'll pay a penalty.

Understanding the Part A premium and what it covers

Most people who have worked and paid Medicare taxes for at least 10 years pay no monthly premium for Part A — it's included in the Medicare package at no cost. If you haven't worked that long in the United States, you may pay a monthly premium that varies based on how many quarters of work history you have.

Part A covers hospital inpatient stays (up to 60 days per benefit period with no copay, then copays for days 61–90), skilled nursing facility care after a hospital stay, home health services, and hospice care. It does not cover outpatient doctor visits, prescription drugs, or routine preventive care — those are covered by Part B and other plans.

If you enroll late and don't have a may have access to reason, your premium increases by 10%. That surcharge applies to every month you're enrolled in Part A for the rest of your life. For someone with a $300 monthly premium, that's an extra $30 per month, or $360 per year, forever.

What happens after you enroll

Once you enroll in Part A, your coverage begins on the first day of the month you turn 65 (or the first day of the month after you enroll, if you enroll after your birthday month). You'll receive your Medicare card in the mail about two weeks before coverage starts.

Your card will show your Medicare number, which you'll use at hospitals, doctors' offices, and when filling prescriptions. Keep it in a safe place — you'll need it for the rest of your life.

After Part A enrollment, you'll also need to make decisions about Part B (medical insurance) and whether to add prescription drug coverage or a supplemental plan. These have their own enrollment windows and important date. Medicare will send you information about these choices, but you're responsible for making them during the correct timeframes.

Frequently Asked Questions

What if I turn 65 while still working?

You can still enroll in Part A during your Initial Enrollment Period, even if you're working and have employer health insurance. Many people do this and keep their employer plan as primary coverage. Part A and your employer plan can work together, with one paying first and the other covering remaining costs.

Can I delay Part A enrollment if I have employer coverage?

Part A has no special rule for employer coverage like Part B does. If you miss your Initial Enrollment Period, you'll face a permanent 10% premium penalty unless you have a may have access to reason for a Special Enrollment Period. It's safest to enroll during your seven-month window even if you plan to keep working.

What if I don't know when my Initial Enrollment Period is?

Call 1-800-MEDICARE and tell them your birth date. They'll tell you the exact month your window opens and closes. You can also create an account at Medicare.gov and check your enrollment status there. It's worth confirming directly rather than guessing, since the penalty for missing it is permanent.

Do I have to enroll in Part B at the same time as Part A?

No. Part A and Part B have separate enrollment windows and separate decisions. You can enroll in Part A without enrolling in Part B, though most people do both. Part B has different rules about late enrollment penalties, so the timing matters for that separately.

What if I'm not a U.S. citizen?

You must be a U.S. citizen or have been a legal resident for at least five continuous years to enroll in Medicare. If you're in the process of becoming a citizen or resident, contact 1-800-MEDICARE to discuss your situation and timeline. They can tell you when you'll be may be able to access and what documents you'll need.